Nucleic acid purification typically consists of a lysis step to release nucleic acids from a sample, the binding of the nucleic acids to a solid matrix, the washing of the matrix to remove contaminating substances and the elution of the nucleic acids from the matrix in a buffer. The process is complex, particularly in the washing of the matrix in the removal of contaminants. Solutions must be added to the matrix which will remove contaminants but not the nucleic acids and then these solutions must be removed prior to the elution of the nucleic acids from the matrix. If magnetic particles are used as the solid matrix, they typically must be captured after the binding step, separated from the lysis-binding solution, either by capture and removal of the particles from the solution or by immobilization of the particles and removal of the lysis-binding solution, and then released into a wash solution. Following the wash the particles must be captured again and separated from the wash solution. See, e.g., Alderton, R. P., et al., Anal. Biochem. (1992) 201:166-169 and WO 91/00212. Some protocols require several wash steps using several different wash solutions. After the particles have been washed, they must be re-suspended in an elution buffer to release the nucleic acids from the particles. Further, these procedures are often not selective for nucleic acids. Rather, a variety of solid and dissolved substances are agglutinated as well.
Other protocols require the precipitation of the nucleic acid with, for example, ethanol. The precipitated nucleic acid must then be washed and resolubilized. Chromatographic procedures also exist for the isolation of nucleic acid (see, e.g., EP 0 658 164) but these procedures also require multiple steps and washes.
The prior art SCODA (Synchronous Coefficient of Drag Alteration) system by Boreal Genomics, Inc. (Los Altos, Calif.) uses a pulsed electronic field to focus nucleic acids into a point but this is typically pre-purified material that may be very dilute. The oil-gate system developed by Kelso at Northwestern University (Sur, et al., Immiscible Phase Nucleic Acid Purification Eliminates PCR Inhibitors with a Single Pass of Paramagnetic Particle through a Hydrophobic Liquid, J. Mol. Diag. 2012 12(5):620-628) drags the particles through oil to try to eliminate washing but the method resulted in substantial salt carry over because the oil left a large droplet of lysis solution around the particles which resulted in a great deal of salt carryover. Thus, additional processing was necessary when using this system.
It can be seen that the methods for the isolation/purification of nucleic acids that are considered state of the art have certain disadvantages. Such disadvantages relate to, e.g., purity, selectivity, recovery rate, laboratory safety and convenience, as well as to the speed of the isolation/purification process. In other words, known prior art procedures require multiple steps and often result in loss of target nucleic acid due to numerous steps and/or alteration of target nucleic acid (for example, loss of modifying groups due to repeated harsh treatment conditions).
Thus, the problem to be solved is to provide a simpler procedure for isolating nucleic acids from a sample that will save time and reagents and help prevent the loss of target and/or modification of the target during processing.